It is known to use shunt inductance windings to increase the stability of the grid by compensating the capacititive reactance of long electricity power transport lines, which are generally high-tension lines.
There are two types of shunt inductance winding: the magnetic barrel type without a core and the iron core type with air gaps. This second type of inductance winding is being used more and more because of the design possibilities it offers users due to its saturation characteristics. The core of such a winding is then constituted by a vertical stack of iron disks separated by air gaps. In a known embodiment, the metal laminations of each iron disk are disposed substantially radially so that, when observed from above, the disks have central holes. The disks are built up from sector-shaped portions. One such portion is constituted by juxtaposing bundles of metal laminations of progressively increasing length per bundle and with the laminations occupying vertical planes. A portion generally includes six to eight bundles in a stepped configuration. In this known disposition, the laminations are so arranged that the direction in which the metal passed through the rolling mill is axial, parallel to the direction of the main magnetic field.
In such a disposition, it is difficult to obtain a filling coefficient of more than 0.8 under acceptable conditions. Then, because of the constraint concerning the alignment of the direction in which the metal lamination passed through the rolling mill with the main magnetic field, it is necessary to have as many rolls of magnetic metal sheet of different widths available as there are bundles of metal laminations of different lengths in a sector-shaped portion. Alternatively only one roll is used whose width corresponds to the length of the longest bundle of metal laminations in a sector-shaped portion but then this makes extra cutting necessary in a perpendicular direction for the shorter bundles, and hence more work and numerous scraps of sheet metal.
The present invention aims to improve the filling coefficient, to facilitate industrial manufacture of the cores, and to minimize the total iron losses due to the main magnetic flux and to the extra losses due to the interference fringes between successive sections.